If `cos^2x+cosx=a+2`, then find the value of a for which equation has – InterviewSolution

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1.	If `cos^2x+cosx=a+2`, then find the value of a for which equation has solution.
Answer» Correct Answer - [-9/4, 0] `cos^2x+cosx=a+2` `rArr (cosx+1/2)^2=a+9/4` Now, `-1/2lecosx+1/2le3/2` `:. (cosx+1/2)^2in[0,9/4]` So, `0lea+9/4le9/4` `:. -9/4leale0`

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